What is up with this fog? Why has it been so foggy for so many days when it’s near freezing?

Matt Elwell, 6News meteorologist, gives us this answer:
“This persistent fog is in place for several reasons: light wind, melting snow and current snowpack. Most fog will form when wind is light, which has been the case with this same airmass over the last several days. We are currently dealing with advection fog, which happens when moist air (a result of warm days causing the snow to melt) moves over a cold surface (or the snowpack that we have in place now). The freezing conditions have very little impact on fog formation, but can make travel more difficult.”